Solder paste droplet ejection apparatus, patterning system having the same, and control method thereof

ABSTRACT

Disclosed herein is a solder paste droplet ejection apparatus including: a nozzle cap forming an appearance and including a heating electric wire provided inside thereof; a nozzle unit formed inside the nozzle cap, spaced apart from the nozzle cap, and surrounded by the nozzle cap; an ejection probe formed inside the nozzle unit, spaced apart from the nozzle unit, and surrounded by the nozzle unit; and a transfer unit formed in a top portion of the nozzle cap and used for a minute movement, wherein a solder paste supplied in a space between the nozzle unit and the ejection probe is ejected in a droplet shape along the ejection probe.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2012-0065049, filed on Jun. 18, 2012, entitled “Solder-Paste DropletEjection Apparatus, Patterning System Having the Same, and ControlMethod Thereof”, which is hereby incorporated by reference in itsentirety into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a solder paste droplet ejectionapparatus, patterning system having the same, and control methodthereof.

2. Description of the Related Art

A solder paste is a core material used to form a solder bump formounting a device onto a PCB. In general, examples of methods of formingthe solder bump are an electroplating method, an inkjet method, a screenprinting method, etc.

Among these methods, the inkjet method is a widely used method in MEMS,a semiconductor process, etc., in addition to a printer, and, inparticular, plays a very important role in an operation of forming abump during a circuit patterning and electronic packaging process usingmetal ink.

However, in order to meet demands of high density, small-sized, and highperformance electronic devices, in particular, a nano-patterning methodcapable of dramatically reducing a nano-patterning operation, andcontrolling a bump size and a pitch interval minutely at a nano-level isneeded.

The conventional nano-patterning technologies that meet such demands area dip-pen using method and a nano-inkjet method disclosed in KoreanPatent Laid-Open Publication No. 2010-0043542 (laid-open published onApr. 29, 2010).

However, these methods are not suitable for forming a pattern of auniform size such as a solder ball.

That is, since the dip-pen using method performs patterning by supplyingink to a tip, a continuous process is impossible, which is problematicin the mass production, and the ink-jet method enables nano-levelpatterning, whereas it takes long time to perform the ink-jet method.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a solderpaste droplet ejection apparatus capable of performing a patterningprocess by continuously ejecting solder paste droplets.

Further, the present invention has been made in an effort to provide apatterning system including a solder paste droplet ejection apparatuscapable of performing a patterning process by continuously ejectingsolder paste droplets.

Further, the present invention has been made in an effort to provide apatterning control method capable of performing a patterning process bycontinuously ejecting solder paste droplets.

According to one preferred embodiment of the present invention, there isprovided a solder paste droplet ejection apparatus, including: a nozzlecap forming an appearance and including a heating electric wire providedinside thereof; a nozzle unit formed inside the nozzle cap, spaced apartfrom the nozzle cap, and surrounded by the nozzle cap; an ejection probeformed inside the nozzle unit, spaced apart from the nozzle unit, andsurrounded by the nozzle unit; and a transfer unit formed at a topportion of the nozzle cap and used for a minute movement, wherein asolder paste supplied in a space between the nozzle unit and theejection probe is ejected in a droplet shape along the ejection probe.

The nozzle cap may be formed in a tube shape having a width narrower ina lower direction, and form a gas path that sprays an inert gas injectedbetween the nozzle cap and the nozzle unit in a direction of an endportion.

The ejection probe may be formed in a shape of a sharp needle in adirection of an end portion by using a metallic material, and beconfigured to protrude from an end portion through hole of the nozzlecap.

The nozzle unit may include a temperature detector for detecting atemperature of the solder paste inside thereof.

The transfer unit may include a piezo-actuator or a motor.

According to another preferred embodiment of the present invention,there is provided a patterning system including: a stage holding atarget and having an electric polarity; a solder paste droplet ejectionapparatus ejecting a solder paste to the target in a droplet shape; apressurizing unit supplying the solder paste from a storage unit of thesolder paste to the solder paste droplet ejection apparatus; a controlunit performing a control on an ejection of the solder paste droplet; agas pumping unit connected to the control unit and supplying an inertgas to the solder paste droplet ejection apparatus; and a display unitconnected to the control unit and displaying control information on anano-patterning operation using the solder paste droplet.

The stage may be connected to the control unit and have an electricpolarity opposite to an electric polarity of the solder pasted dropletejection apparatus.

The solder pasted droplet ejection apparatus may include: a nozzle capforming an appearance and including a heating electric wire providedinside thereof; a nozzle unit formed inside the nozzle cap, spaced apartfrom the nozzle cap, and surrounded by the nozzle cap; an ejection probeformed inside the nozzle unit, spaced apart from the nozzle unit, andsurrounded by the nozzle unit; and a transfer unit formed in a topportion of the nozzle cap and used for a minute movement, wherein asolder paste supplied in a space between the nozzle unit and theejection probe is heated by the heating electric wire and is ejected ina droplet shape along the ejection probe by the pressurizing unit

The control unit may control a voltage applied to the ejection probe andcontrol a size of the solder paste droplet.

The control unit may adjust a pulse width of the voltage and applies thevoltage.

The nozzle cap may be formed in a tube shape having a width narrower ina lower direction, and form a gas path that sprays an inert gas that issupplied from the gas pumping unit and is injected between the nozzlecap and the nozzle unit in a direction of an end portion.

The ejection probe may be formed in a shape of a sharp needle in adirection of an end portion by using a metallic material, and beconfigured to protrude from an end portion through hole of the nozzlecap.

The nozzle unit may include a temperature detector for detecting atemperature of the solder paste inside thereof.

According to another preferred embodiment of the present invention,there is provided a patterning control method including: preheating, bya control unit, a solder paste supplied to a solder paste dropletejection apparatus to change the solder paste into a melting state;ejecting, by the control unit, the melted solder paste onto a target ina minute droplet shape by using a voltage applied to the solder pastedroplet ejection apparatus or an inert gas; determining, by the controlunit, whether a size of a pattern formed in the target by the ejectedminute droplet is a desired size; and according to a determinationresult that the size of the pattern is not the desired size, ejecting,by the control unit, the solder paste in the minute droplet shape againbased on ejection conditions corrected on the solder paste dropletejection apparatus.

In the preheating, the control unit may apply a voltage to a heatingelectric wire included in a nozzle cap forming an appearance of thesolder paste droplet ejection apparatus to change the solder pastecontained in the solder paste droplet ejection apparatus into themelting state.

In the preheating, the control unit may apply electric polarities to astage holding the target and the solder paste droplet ejection apparatusto generate an electrostatic force between the target and the solderpaste droplet ejection apparatus.

In the ejecting of the melted solder paste onto the target in the minutedroplet shape, the control unit may set an ejection application voltageapplied to an ejection probe of the solder paste droplet ejectionapparatus, a pulse waveform of the ejection application voltage, and adistance between the ejection probe and the target to eject the meltedsolder paste in the minute droplet shape.

The ejection application voltage V may be applied as a numerical valuehaving a range of

${h\sqrt{\frac{\gamma \; \pi}{ɛ_{0}d}}} > V > \sqrt{\frac{\gamma \; {kd}}{2\; ɛ_{0}}}$

(γ: surface tension [N/m] of melted solder paste, ε₀: dielectricpermittivity [F/m] of vacuum, d: diameter of a sharp end portion of anejection probe, h: distance between the ejection probe and a target, k:proportional constant).

In the ejecting of the melted solder paste onto the target in the minutedroplet shape, the minute droplet that is being formed may be ejected byusing a spray pressure of the inert gas injected into the solder pastedroplet ejection apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic view of a construction of a patterning systemincluding a solder paste droplet ejection apparatus according to anembodiment of the present invention;

FIG. 2A is an exemplary view for explaining an operation principle of asolder paste droplet ejection apparatus according to an embodiment ofthe present invention;

FIG. 2B is a cross-sectional view of a nozzle unit of a solder pastedroplet ejection apparatus according to an embodiment of the presentinvention;

FIG. 3 is a bottom view of a nozzle cap of a solder paste dropletejection apparatus according to an embodiment of the present invention;and

FIG. 4 is a flowchart of a patterning control method of performing apatterning process by ejecting a solder paste according to anotherembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects, features and advantages of the present invention will bemore clearly understood from the following detailed description of thepreferred embodiments taken in conjunction with the accompanyingdrawings. Throughout the accompanying drawings, the same referencenumerals are used to designate the same or similar components, andredundant descriptions thereof are omitted. Further, in the followingdescription, the terms “first”, “second”, “one side”, “the other side”and the like are used to differentiate a certain component from othercomponents, but the configuration of such components should not beconstrued to be limited by the terms. Further, in the description of thepresent invention, when it is determined that the detailed descriptionof the related art would obscure the gist of the present invention, thedescription thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view of a construction of a patterning systemincluding a solder paste droplet ejection apparatus according to anembodiment of the present invention. FIG. 2A is an exemplary view forexplaining an operation principle of a solder paste droplet ejectionapparatus according to an embodiment of the present invention. FIG. 2Bis a cross-sectional view of a nozzle unit of a solder paste dropletejection apparatus according to an embodiment of the present invention.FIG. 3 is a bottom view of a nozzle cap of a solder paste dropletejection apparatus according to an embodiment of the present invention.In this regard, although the patterning system according to anembodiment of the present invention exemplarily patterns a solder pasteon a target such as a printed circuit board by a solder bump, thepresent invention is not limited thereto. A variety of patternsincluding a nano-level conductive pattern may be formed on a substrateby using a conductive paste.

Referring to FIG. 1, the patterning system according to an embodiment ofthe present invention includes a stage 100 that holds a target 110 suchas a printed circuit board and has an electrical polarity, a solderpaste droplet ejection apparatus 200, a pressurizing unit 300 thatsupplies a solder paste 410 to the solder paste droplet ejectionapparatus 200 from a storage unit 400, a control unit 500 that performsa general control on ejection of the solder paste 410, a gas pumpingunit 600 that is connected to the control unit 500 and supplies an inertgas to the solder paste droplet ejection apparatus 200, and a displayunit 700 that is connected to the control unit 500 and displays controlinformation of a nano-patterning operation.

The solder paste droplet ejection apparatus 200 may form the solderpaste 410 of the storage unit 400 supplied by the pressurizing unit 300in minute droplets at an end portion of an ejection probe 220 by anelectrostatic force according to a control of the control unit 500. Theformed minute droplets of the solder paste 410 may be ejected onto thetarget 110 by the electrostatic force or the inert gas.

More specifically, the solder paste droplet ejection apparatus 200 mayinclude a nozzle cap 210 forming an appearance and in which a heatingelectric wire 212 is coiled inside, a nozzle unit 230 spaced toward theinside of the nozzle cap 210 so as to form a gas path 250 inside thenozzle cap 210, an ejection probe 220 surrounded by the nozzle unit 230,and a transfer unit 260 formed in an upper portion used for a minutemovement.

As shown in FIG. 2A, the nozzle cap 210 has a cylindrical exteriorshape, is spaced apart from and surrounds the nozzle unit 230, and is ina tube shape having a width narrower in a direction of the end portion.The gas path 250 is formed between the nozzle cap 210 and the nozzleunit 230. Also, the nozzle cap 210 includes the heating electric wire212 by forming through holes 211 to the end portion along an innerportion of the boundary. The heating electric wire 212 may be includedin the through holes 211 so that the nozzle cap 210 may perform aheating function by electric heating of the heating electric wire 212.

Accordingly, the nozzle cap 210 may be formed of a material of heatresistance that is not modified by a high temperature and to which thesolder paste 410 is not bonded well, for example, a metal material suchas AL, stainless steel, a ceramic material, or a polymer material suchas plastic.

The nozzle cap 210 may heat the solder paste 410 contained in the nozzleunit 230 by a heating function and change the solder paste 410 into amelting state.

The nozzle unit 230 surrounds the ejection probe 220, places the solderpaste 410 supplied by the pressurizing unit 300 in a space between thenozzle unit 230 and the ejection probe 220, and induces the solder paste410 in a direction of an end portion of the ejection probe 220. In thisregard, the solder paste 410 placed in the space between the nozzle unit230 and the ejection probe 220 may smoothly flow in the direction of theend portion of the ejection probe 220 in the melting state by theheating function of the nozzle cap 210.

Also, the nozzle unit 230 may include a temperature detector such as aplatinum resistance thermometer, a thermocouple, an infraredthermometer, etc. in order to detect a melting temperature of the solderpaste.

The ejection probe 220 is formed of a metal material and has a sharpneedle shape inside the nozzle unit 230. The ejection probe 220 havingthe above structure may be configured to protrude from a leading portionthrough hole of the nozzle cap 210 through an end portion through holeof the nozzle unit 230.

As shown in FIG. 2A, an electric field is formed by applying a polarityopposite to a polarity of the stage 100 to the ejection probe 220, andthe melted solder paste 410 flows out along a surface of the ejectionprobe 220 by the electric field, so that the solder paste 410 forms aminute droplet 411 having charges at a leading portion of the ejectionprobe 220 as shown in FIG. 2B.

In this regard, to minimize evaporation of the minute droplet 411,evaporation of the solder paste 410 that flows out along the surface ofthe ejection probe 220 may be minimized by minimizing a spaced gap Lbetween the ejection probe 220 and the nozzle cap 210 shown in FIG. 3.

The minute droplet 411 is ejected onto the target 110 by a voltageapplied to the ejection probe 220 or the inert gas sprayed through thegas path 250.

In this regard, if the end portion of the ejection probe 220 is reducedin a sub-micro unit or a nano unit, an intensity of an electric fieldincreases by the electrostatic force and thus the minute droplet 411 iseasily ejected.

Also, the minute droplet 411 may obtain an ejection straightness of astable track to the target 110 by the electrostatic force formed betweenthe ejection probe 220 and the target 110, thereby increasing precisionof an impact location of the ejected minute droplet 411.

Therefore, the ejection probe 220 may be used to form the minute droplet411 and stably eject the minute droplet 411, and thus a bump having aminute size necessary for a packaging process is formed, and a pitchinterval is minutely controlled.

The transfer unit 260 may be connected to the control unit 500 include apiezo-actuator or motor moves to X-Y-Z axes, and may preferably use apiezo-actuator capable of a minute control of a movement length.

The control unit 500 may be connected to the elements of the patterningsystem to generally control the nano patterning operation, inparticular, form the minute droplet 411 of the solder paste 410 by usingthe solder paste droplet ejection apparatus 200, and control anoperation of ejecting the minute droplet 411 of a set size to the target110.

The above-described patterning system according to an embodiment of thepresent invention may maintain the viscosity solder paste 410 higherthan a melting temperature by the nozzle cap 210 surrounding the nozzleunit 230 when the minute droplet 411 of the solder paste 410 is ejectedfrom the nozzle unit 230 through the ejection probe 220, and prevent atemperature reduction of the solder paste 410 and an ejection block ofthe nozzle unit 230 by minimizing a room temperature standby contactsurface of the ejection probe 220.

Also, the patterning system according to an embodiment of the presentinvention may prevent a composition of the solder paste 410 fromchanging due to generation of a gas, evaporation thereof, oxidationthereof by heating by injecting and spraying the inert gas such asnitrogen, argon, etc., into the gas path 250 formed between the nozzlecap 210a and the nozzle unit 230 through the gas pumping unit 600.

Further, the patterning system according to an embodiment of the presentinvention may minimize evaporation of the solder paste 410 that flowsdown along the surface of the ejection probe 220 by minimizing thespaced gap distance between the ejection probe 220 and the nozzle cap210.

Hereinafter, a patterning control method capable of ejecting the solderpaste 410 and performing a patterning operation according to anotherembodiment of the present invention will now be described with referenceto FIG. 4. FIG. 4 is a flowchart of a patterning control method ofperforming a patterning process by ejecting a solder paste according toanother embodiment of the present invention.

The patterning control method according to another embodiment of thepresent invention performs a preheating operation to change the solderpaste 410 to a melting state (S410).

More specifically, the control unit 500 may preheat the solder paste 410contained between the ejection probe 220 and the nozzle unit 230 to themelting state by applying a voltage to the heating electric wire 212included in the nozzle cap 210.

In this regard, the control unit 500 may generate an electrostatic forcebetween the target 110 and the ejection probe 220 by applying electricpolarities to the stage 100 holding the target 110 such as a printedcircuit board and the ejection probe 220.

Accordingly, the minute droplet 411 of the solder paste 410 formed in anend portion of the ejection probe 220 has charges, and the control unit500 ejects the minute droplet 411 to the target 110 by using a voltage(hereinafter referred to as an “ejection application voltage V”) appliedto the ejection probe 220 or an inert gas injected into the gas path 250(S420).

More specifically, the ejection application voltage V applied to theejection probe 220 is controlled and applied according to Equation 1below.

$\begin{matrix}{{h\sqrt{\frac{\gamma \; \pi}{ɛ_{0}d}}} > V > \sqrt{\frac{\gamma \; {kd}}{2\; ɛ_{0}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

(γ: surface tension [N/m] of melted solder paste, ε₀: dielectricpermittivity [F/m] of vacuum, d: diameter of a sharp end portion of anejection probe, h: distance between the ejection probe and a target, k:proportional constant)

In Equation 1 above, a left term indicates a lowest ejection voltage ina case where a droplet is generally ejected by using an electric fieldbetween electrodes, and a right term indicates a lowest ejection voltageaccording to another embodiment of the present invention.

In consideration of an effect that the electric field focuses on thesharp end portion of the ejection probe 220, in Equation 1 above, as thediameter d of the sharp end portion of the ejection probe 220 isreduced, the ejection application voltage V is reduced in proportionalto the diameter d, and thus the minute droplet 411 may be ejected at thelow ejection application voltage V.

Also, since a size of the minute droplet 411 may be controlled by apulse width of an ejection voltage, if a voltage of a single pulsewaveform is applied to the ejection probe 220 at a time interval duringan operation of forming the minute droplet 411, the size of the minutedroplet 411 that is being formed may be minutely adjusted and the minutedroplet 411 may be ejected.

Alternatively, the minute droplet 411 that is being formed may beejected by using a spray pressure of the inert gas injected into the gaspath 250.

After the minute droplet 411 is ejected onto the target 110, it isdetermined whether a size of a solder pattern formed in the target 110by the ejected minute droplet 411 is a desired size (S430).

For example, to determine whether the size of the solder pattern is thedesired size, the control unit 500 may analyze image information of thesolder pattern formed in the target 110 by using a separately connectedimaging apparatus (not shown) to determine whether the size of thesolder pattern is the desired size of a nano unit.

If it is determined that the size of the solder pattern is not thedesired size, the control unit 500 corrects ejection conditions based onEquation 1 above to eject the minute droplet 411 for forming the solderpattern of the desired size (S440).

That is, the control unit 500 may correct the ejection conditionsincluding the ejection application voltage V applied to the ejectionprobe 220, the distance h between the ejection probe 220 and the target110, the single pulse waveform of the ejection application voltage, etc.to eject the minute droplet 411 for forming the solder pattern of thedesired size.

In particular, the control unit 500 adjusts a time interval in thesingle pulse waveform of the ejection application voltage to minutelyadjust the size of the minute droplet 411, thereby forming the solderpattern of the desired size.

As the minute droplet 411 is ejected to form the solder pattern of thedesired size, the control unit 500 continues to eject the minute droplet411 and performs the operation of forming the solder pattern including asolder bump, etc. while minutely moving the solder paste dropletejection apparatus 200 through the transfer unit 260 (S450).

Accordingly, the patterning control method according to anotherembodiment of the present invention may easily form the solder patternincluding a minute solder bump, etc. in a sub-micro unit or a nano unitby adjusting the size of the minute droplet 411.

Therefore, the patterning control method according to another embodimentof the present invention forms the minute droplet 411 of the nano unitthrough the ejection probe 220, and stably ejects the minute droplet411, thereby forming a solder bump of a minute size necessary for apackaging process and minutely controlling a pitch interval.

As described above, the patterning system according to the presentinvention forms a solder paste in a minute droplet and stably ejects theminute droplet by using a solder paste droplet ejection apparatus,thereby forming a bump of a minute size necessary for a packagingprocess and minutely controlling a pitch interval.

The patterning control method according to the present invention adjustsa solder paste in a minute droplet size and ejecting the minute dropletby using an ejection application voltage applied to a solder pastedroplet ejection apparatus, thereby easily forming a solder patternincluding a minute solder bump, etc.

Although the embodiments of the present invention have been disclosedfor illustrative purposes, it will be appreciated that the presentinvention is not limited thereto, and those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the invention.

Accordingly, any and all modifications, variations or equivalentarrangements should be considered to be within the scope of theinvention, and the detailed scope of the invention will be disclosed bythe accompanying claims.

What is claimed is:
 1. A solder paste droplet ejection apparatus,comprising: a nozzle cap forming an appearance and including a heatingelectric wire provided inside thereof; a nozzle unit formed inside thenozzle cap, spaced apart from the nozzle cap, and surrounded by thenozzle cap; an ejection probe formed inside the nozzle unit, spacedapart from the nozzle unit, and surrounded by the nozzle unit; and atransfer unit formed in a top portion of the nozzle cap and used for aminute movement, wherein a solder paste supplied in a space between thenozzle unit and the ejection probe is ejected in a droplet shape alongthe ejection probe.
 2. The solder paste droplet ejection apparatus asset forth in claim 1, wherein the nozzle cap is formed in a tube shapehaving a width narrower in a lower direction, and forms a gas path thatsprays an inert gas injected between the nozzle cap and the nozzle unitin a direction of an end portion.
 3. The solder paste droplet ejectionapparatus as set forth in claim 1, wherein the ejection probe is formedin a shape of a sharp needle in a direction of an end portion by using ametallic material, and is configured to protrude from an end portionthrough hole of the nozzle cap.
 4. The solder paste droplet ejectionapparatus as set forth in claim 1, wherein the nozzle unit includes atemperature detector for detecting a temperature of the solder pasteinside thereof.
 5. The solder paste droplet ejection apparatus as setforth in claim 1, wherein the transfer unit includes a piezo-actuator ora motor.
 6. A patterning system comprising: a stage holding a target andhaving an electric polarity; a solder paste droplet ejection apparatusejecting a solder paste to the target in a droplet shape; a pressurizingunit supplying the solder paste from a storage unit of the solder pasteto the solder paste droplet ejection apparatus; a control unitperforming a control on an ejection of the solder paste droplet; a gaspumping unit connected to the control unit and supplying an inert gas tothe solder paste droplet ejection apparatus; and a display unitconnected to the control unit and displaying control information on anano-patterning operation using the solder paste droplet
 7. Thepatterning system as set forth in claim 6, wherein the stage isconnected to the control unit and has an electric polarity opposite toan electric polarity of the solder pasted droplet ejection apparatus. 8.The patterning system as set forth in claim 6, wherein the solder pasteddroplet ejection apparatus includes: a nozzle cap forming an appearanceand including a heating electric wire provided inside thereof; a nozzleunit formed inside the nozzle cap, spaced apart from the nozzle cap, andsurrounded by the nozzle cap; an ejection probe formed inside the nozzleunit, spaced apart from the nozzle unit, and surrounded by the nozzleunit; and a transfer unit formed in a top portion of the nozzle cap andused for a minute movement, wherein a solder paste supplied in a spacebetween the nozzle unit and the ejection probe is heated by the heatingelectric wire and is ejected in a droplet shape along the ejection probeby the pressurizing unit.
 9. The patterning system as set forth in claim8, wherein the control unit controls a voltage applied to the ejectionprobe and controls a size of the solder paste droplet.
 10. Thepatterning system as set forth in claim 9, wherein the control unitadjusts a pulse width of the voltage and applies the voltage.
 11. Thepatterning system as set forth in claim 8, wherein the nozzle cap isformed in a tube shape having a width narrower in a lower direction, andforms a gas path that sprays an inert gas that is supplied from the gaspumping unit and is injected between the nozzle cap and the nozzle unitin a direction of an end portion.
 12. The patterning system as set forthin claim 8, wherein the ejection probe is formed in a shape of a sharpneedle in a direction of an end portion by using a metallic material,and is configured to protrude from an end portion through hole of thenozzle cap.
 13. The patterning system as set forth in claim 8, whereinthe nozzle unit includes a temperature detector for detecting atemperature of the solder paste inside thereof.
 14. The patterningsystem as set forth in claim 8, wherein the transfer unit includes apiezo-actuator or a motor.
 15. A patterning control method comprising:preheating, by a control unit, a solder paste supplied to a solder pastedroplet ejection apparatus to change the solder paste into a meltingstate; ejecting, by the control unit, the melted solder paste onto atarget in a minute droplet shape by using a voltage applied to thesolder paste droplet ejection apparatus or an inert gas; determining, bythe control unit, whether a size of a pattern formed in the target bythe ejected minute droplet is a desired size; and according to adetermination result that the size of the pattern is not the desiredsize, ejecting, by the control unit, the solder paste in the minutedroplet shape again based on ejection conditions corrected on the solderpaste droplet ejection apparatus.
 16. The patterning control method asset forth in claim 15, wherein in the preheating, the control unitapplies a voltage to a heating electric wire included in a nozzle capforming an appearance of the solder paste droplet ejection apparatus tochange the solder paste contained in the solder paste droplet ejectionapparatus into the melting state.
 17. The patterning control method asset forth in claim 15, wherein in the preheating, the control unitapplies electric polarities to a stage holding the target and the solderpaste droplet ejection apparatus to generate an electrostatic forcebetween the target and the solder paste droplet ejection apparatus. 18.The patterning control method as set forth in claim 15, wherein in theejecting of the melted solder paste onto the target in the minutedroplet shape, the control unit sets an ejection application voltageapplied to an ejection probe of the solder paste droplet ejectionapparatus, a pulse waveform of the ejection application voltage, and adistance between the ejection probe and the target to eject the meltedsolder paste in the minute droplet shape.
 19. The patterning controlmethod as set forth in claim 18, wherein the ejection applicationvoltage V is applied as a numerical value having a range of${h\sqrt{\frac{\gamma \; \pi}{ɛ_{0}d}}} > V > \sqrt{\frac{\gamma \; {kd}}{2\; ɛ_{0}}}$(γ: surface tension [N/m] of melted solder paste, ε0: dielectricpermittivity [F/m] of vacuum, d: diameter of a sharp end portion of anejection probe, h: distance between the ejection probe and a target, k:proportional constant).
 20. The patterning control method as set forthin claim 15, wherein in the ejecting of the melted solder paste onto thetarget in the minute droplet shape, the minute droplet that is beingformed is ejected by using a spray pressure of the inert gas injectedinto the solder paste droplet ejection apparatus.